A number of different companies manufacture imaging devices such as copiers, printers, fax machines, or all in one devices that perform all of these functions. These imaging devices typically use light to illuminate a light sensitive drum which is coated with a material that causes the illuminated area to differentially charge when compared to the un-illuminated areas of the drum. This differential charge forms a latent image on the cylinder or drum. Toner is attracted to this latent image on the surface of the drum, and then is transferred through well known processes to some media such as paper.
The light sensitive drum originally was a selenium coated drum. For cost and environmental reasons the selenium coating has been replaced with a variety of organic chemical materials. The resulting product is known as an organic photoconductive drum. Organic photoconductive drums are used and sold by both the makers of new products, and by companies that repair used products. New organic photoconductive drums may be sold as part of a toner cartridge, as part of a drum cartridge, or as a stand alone replacement unit. These new organic photoconductive drums may be made by the original equipment manufacturers (OEMs) or by different aftermarket companies.
Companies or individuals that repair used products may reuse the existing organic photoconductive drum, or they may replace that organic photoconductive drum with a new aftermarket drum. These companies or individuals who repair used products containing used organic photoconductive drums are sometimes known as remanufacturers. It is obviously more expensive for a remanufacturer to replace an organic photoconductive drum than it is to reuse the old one. However, used organic photoconductive drums are often unusable. The surface is worn during use because abrasive toners rub against the surface, a wiper or cleaner blade presses against the surface of the used organic photoconductive drum as it cleans un-consumed toner from the surface of the organic photoconductive drum, and a primary charge roller rolls against the surface of the organic photoconductive drum during the initial cycle. In some cartridges a developer roller may also contact the surface of the organic photoconductive drum. As a result a used organic photoconductive drum often exhibits gouges, cracks or crazing in the surface layer of the organic photoconductive drum. These wear defects may show up as print defects if the drum is reused. Even if the wear defects are not visible many remanufacturers are unwilling to take the risk of re-using a used organic photoconductive drum because the wear defects could appear in the middle of the next cycle of the organic photoconductive drum.
A number of companies offer products that purport to allow used organic photoconductive drums to be re-used. These substances include powdered PTFE that are applied with a solvent that evaporates. One such product is Slide Coat offered by Anakenesis Technologies, Inc. There are two difficulties with this product. First, it does not work well as the lubricating material appears to be cleaned off of the drum during the second cycle by the wiper blade. Second, powdered PTFE is a hazardous material, which if inhaled can cause flu like symptoms. Another powder based coating is Methuselah powder; a mica based product referenced in U.S. Pat. No. 5,308,515. While the mica based Methuselah power is non-hazardous, and is lubricious, it does not restore the electrical characteristics of the used photoconductive drum. In addition, as will all the powders it is subject to being cleaned off of the surface of the organic photoconductive drum by the wiper blade. Other products on the market place a new solid resin coating on the surface of the used organic photoconductive drum. One example of a polymer resin is QuiCoat offered by LPS Technologies. QuiCoat is a heat cured resin material. These recoating resins do not perform well in a remanufacturing setting. They protect the surface of the used organic photoconductive drum from additional wear, but are difficult to evenly apply frequently putting the organic photoconductive drum slightly out of round due to sag in the resin during the cure. In addition, these resin coatings are typically too resistive, and change the electrical characteristics of the used organic photoconductive drum in unfavorable ways.